Conventionally, although transistors are miniaturized mainly by a logic device, in memory devices which are miniaturized by one generation about every two years, transistors having a performance higher than the logic device have been requested.
In miniaturized transistors, a thin source/drain region such as, for example, a source/drain region having a thickness of 10 nm or less is formed. Even in the transistors, since it is necessary to reduce a parasitic resistance of the transistors, a nickel silicide film is formed on the source/drain region by self-alignment, and a resistance of the source/drain region is reduced by the nickel silicide films.